Pyoderma Gangrenosum (PG)


What is pyoderma gangrenosum (PG)?

Pyoderma gangrenosum (PG) is a chronic, recurrent skin disorder in which patients get small red bumps or blisters that can grow and join together to become large open sores, or ulcers. The number of ulcers that patients get can vary from a few in mild cases to many in more severe ones. They can be quite painful for some patients. PG is often associated with other systemic diseases, as discussed below.

Who gets pyoderma gangrenosum (PG)?

PG is more common in women than in men. Some sources say that PG most commonly affects people who are between 20 and 50 years of age, while others say it skews toward adults 50 and older. Sources agree that it is rare in children. It is estimated that PG affects one in every 100,000 people in the United States.

Symptoms and Causes

What causes pyoderma gangrenosum (PG)?

The cause of PG is not entirely understood. More than half of the people with PG also have another condition, such as arthritis, some cancers (such as leukemia or lymphoma), ulcerative colitis, or Crohn’s disease. PG may be an autoimmune disorder, which means that it is caused by the body fighting against itself for some reason. For some patients, PG will improve as their other systemic diseases are treated.

In addition to being linked to certain autoimmune conditions, PG is often seen after an injury to the skin (trauma or surgery for example). This is called pathergy.

What are the signs and symptoms of pyoderma gangrenosum (PG)?

While PG is most commonly seen on the shins or ankles, it can appear on any part of the body. After the legs, it is seen most often on the arms, genitals, or neck. It usually begins as small red or purple pus-filled blisters that spread quickly. They often swell into open sores that have a distinct blue or violet border. These ulcers may be large and deep and can be very painful.

There are many types of PG, including classic PG described above. Other forms of PG include atypical or bullous PG, which usually causes superficial blisters on the face and hands, pustular PG, which causes small pus bumps, and vegetative PG, which usually involves ulcers that are not painful. PG may also form around stoma sites (peristomal PG).

Some people with PG will also get a fever, have tenderness around the rash/sores, have joint pain, and just may not feel well overall.

Diagnosis and Tests

How is pyoderma gangrenosum (PG) diagnosed?

PG can be difficult to diagnose. No single test can confirm a diagnosis, so doctors often order tests to rule out other possible causes of a patient’s skin problems. Diseases that must be ruled out include:

These tests can include blood tests, biopsies, bone marrow sampling, and even examinations of your rectum and colon to look for possible diseases that could be causing the problem.

Once all other possible causes of the blisters and sores have been ruled out, a doctor can make a diagnosis of PG based on what he or she observes on the patient’s skin.

Management and Treatment

How is pyoderma gangrenosum (PG) treated?

Early diagnosis and treatment is important because PG can leave patients with unpleasant scars if not treated. The condition can go from minor to serious in as little as a day or two. Doctors should consider PG as a possible explanation any time an ulcer or wound does not heal as expected. Primary care doctors should consider referring patients who they suspect of having PG to a dermatologist for a second opinion and treatment.

There are many possible treatment options. In mild disease, physicians can prescribe topical medications that are applied to the skin as the first step. Some recommend that patients wrap the skin with bandages to keep the medication from being disturbed.

For more serious cases, physicians may try immunosuppressive medications that are taken orally, such as prednisone or cyclosporine. Some studies have shown that using “biologic agents" that target specific inflammatory proteins may work. Examples include infliximab, adalimumab, and ustekinumab. Some physicians also report success with antibiotics and hyperbaric oxygen therapy, but these are not widely used methods.

Any injury can potentially make PG worse. Trying to remove the affected skin or “debriding” the ulcer may worsen PG but is sometimes performed depending on the circumstances.

Some patients may need pain relievers to help keep them comfortable until their PG improves.


How can pyoderma gangrenosum (PG) be prevented?

If you have any of the risk factors for PG, such as leukemia or inflammatory bowel disease, be sure to let your physician know right away if you develop any skin problems. PG can move quickly and leave permanent scars. Consider asking for a referral to a dermatologist if your skin continues to worsen.

If you have had PG in the past, be sure to discuss this with any physician who is considering a procedure that will damage your skin (such as surgery) so he or she can consider if the benefits of the procedure outweigh the risks of triggering PG.

Last reviewed by a Cleveland Clinic medical professional on 10/18/2018.


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  • National Organization for Rare Diseases. Pyoderma gangrenosum. Accessed 10/23/2018.
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  • Patel F, Fitzmaurice S, Duong C, et al. Effective strategies for the management of pyoderma gangrenosum: a comprehensive review. Acta Derm Venereol. 2015;95(5):525-31.
  • Callen, J.P., Pyoderma gangrenosum. The Lancet. 1998. 351 (9102). 581-85.

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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy